The present invention relates generally to mounting electronic devices.
FIG. 1 illustrates aspects of a conventional multi-die package. The package has a power die 110 and a control die 120, both of which are secured to a mounting surface (commonly called a “flag” 130).
In many applications, the power die 110 and the control die 120 must be electrically isolated. One conventional method is to attach at least one die (such as the control die 120) to the flag 130 with a non-conductive epoxy compound (not seen). Typically, the epoxy compound is applied by placing dots of epoxy compound on the flag 130 and then using pressure to push the control die 120 onto the flag 130. The epoxy compound is squeezed out evenly under the control die 120. If the epoxy compound layer is too thin, however, there is not enough electrical isolation. This may cause the control die 120 or the power die 110 to short.
To electrically isolate the control die 110 and the power die 120 by physically isolating the mounting surfaces of the control die 110 and the power die 120 has proven to be difficult or costly. First, to simply create two separate mounting surfaces and then attach each of those mounting surfaces to another leadframe (not illustrated), requires more components than a single flag 130. This increases cost and forces a larger package size.
Furthermore, stamping two mounting surfaces out of a single material is constrained because stamping causes the stamped material to become bent or deformed. This deformation interferes with the assembly and operation of the electronic package. Thus, the thicker the material to be stamped, the greater the required physical isolation of the two mounting surfaces. This drives up the total size of the package.